Various adhesives have so far been used for bonding adherends to substrates. Specific examples of the adhesives include solvent rubber-based adhesives, emulsion adhesives, and epoxy resin adhesives, among others.
Solvent rubber-based adhesives can bond adherends to substrates by taking a certain open time after application, without temporary tacking. However, the adhesives contain a solvent, hence are disadvantageous in view of the toxicity thereof to human bodies and the possibility of fire hazards, among others.
For solving the solvent-related problems, aqueous emulsion adhesives have been studied. They are, however, weak in initial adhesion and require temporary tacking. At present, they are thus not at a satisfactory level as yet. Japanese Kokai Publication Hei-03-263478 proposes a novel method of adhesion of a solvent-free contact type. This comprises the use of a moisture-curable adhesive comprising a hydrolyzable silyl group-containing polyoxyalkylene polymer and a hydrolyzable silyl group-containing (meth)acrylic ester copolymer and, like with solvent rubber-based adhesives, can effect bonding without temporary tacking of adherends after the lapse of a certain open time. However, that adhesive has a problem; a certain open time is required, namely fast bonding is impossible.
For shortening the open time, Japanese Kokai Publication Hei-04-312671 proposes a novel method of solvent-free adhesion. This comprises the combined use of a double-sided pressure sensitive adhesive tape and a solvent-free mastic type adhesive. The double-sided pressure sensitive adhesive tape enables temporary tacking of boards to substrates, so that no open time or temporary tacking is required. Further, permanent fixation is attained with solvent-free adhesive, hence no solvent odor problem arises. However, this method of adhesion still has problems. Thus, when the substrate surface is uneven, the contacting of the double-sided pressure sensitive adhesive tape may become insufficient and the adherend may go out of position. For bonding one adherend, operations are required for pressure sensitive adhesive sticking and adhesive application, raising a labor and time problem.
Under such circumstances, a method of adhesion by which adherends can be bonded to substrates without temporary tacking after application and without requiring any open time and, further, the workability is also improved has been demanded.